The petition alleges that the weight sensor in the passenger seat can malfunction and disable air bags before a crash. It says GM used the same system in other models from 2004 through 2010.

The agency says it evaluated the complaint but hasn't found a defect. But as a precaution, it will seek more data from GM on Impalas from model years 2007 through 2009. The inquiry covers about 320,000 cars.

GM spokesman Alan Adler says the company reviewed the issue and decided no action was needed.